Elevators are very common for higher buildings of three or four floors generally with a single elevator which is movable from each floor to the next in accordance with demand. Taller buildings generally have more elevators to service the increased number of occupants of the building with the elevators operating independantly except that there may be some programming of the system by which the elevators wait at particular positions when not in use.
Bungalows and single level apartments are very popular because there is no need for the occupants to move from one level to another using a stairway and all of the features of the building are then available on one level.
Further, for attractiveness and building efficiency, single family dwellings have become more often two storey buidings with of course a stairway connecting the two floors. Stairways are of course effective and very quick for the able bodied person but as the occupants become older the stairway often becomes inconvenient and time consuming so that the older occupants often prefer to move to a bungalow or similar single storey dwelling.
There has been very little attention given to the possibility of providing an efficient elevator system for a simple two storey building such as a single family dwelling. Elevator systems for disabled persons are available but generally this operate on the stairway and are very slow and inconvenient so that the able bodied person certainly would not wish to utilize an arrangement of this type.
It is believed that there has been very little attention to such elevator systems for two storey buildings because the system employed is not sufficiently efficient in time to make its adoption worthwhile. Furthermore the elevator system is generally relatively expensive in view of the necessity to reinforce the structure of the building to carry the weight involved in the movement of the carriage.